Trying to get my car to idle right

[85begalttype]

Idles good when cold still high(1000rpm), but when it warms up, its all over the place from 1000 to 1500rpm, will stay steady for 10 seconds, then bounce high then go back down.

I cant afford a scan tool right now, i took out the IAC plunger and cleaned it and seemed to help a little. i grounded the ALDL connecter and got code 15(COOLANT TEMPERATURE SENSOR CIRCUIT (LOW TEMP)) and code 45(OXYGEN SENSOR CIRCUIT ( RICH EXHAUST)).

Anything i can do with a digi meter, tps is around 0.42. Is that torx screw behind the top of the throttle body a throttle stop screw or iac adjustment?



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85 T-type bone stock

 

[T-Type85David]

BAD O2 im gonna say, Scan tools are a pretty penny. had this problem. I had spare TPS/IAC sensors, drop those in and did the trick. When you cleaned the IAC did you let it dry all the way or just clean n throw in back in? I heard that can mest up your idle. Sounds to me like a bad O2, not getting into closed mode or some other. If you have a spare change it out and see if it makes any difference?? if not, DENSO 26.00 at autzone. running a bit HOT? This is just my .02, sure someone can go into more detail about this with you.

 

[85begalttype]

I let the IAC dry out. Im ordering a o2 sensor now, see if that does the trick. Also is there a way to test the Coolant temp sensor, i ran an ohm meter across the two terminals on the sensor and it shows that there is no circuit between the two terminals. thanks so far!

 

[Jerryl]

I let the IAC dry out. Im ordering a o2 sensor now, see if that does the trick. Also is there a way to test the Coolant temp sensor, i ran an ohm meter across the two terminals on the sensor and it shows that there is no circuit between the two terminals. thanks so far!

You need a scantool, or just replace it.
Here is a link to diagnostics ........
Vortex Turbo Buick Performance
On the left, select "Troubleshooting" and start there.
GREAT site!

FWIW ....... I helped my neighbor with a smiliar coolant temp issue on his motorhome.
The brand new sensor from O'Reily was defective!
Exchanged it, and all went well.
This is why I keep the OTC4000 around.